The bi-phase modulation encoding technology is a common encoding technology to transmit data. FIG. 1 illustrates bi-phase modulation encoding technology. As shown in FIG. 1, every bit window (i.e., bit cycle) of the bi-phase modulated signal represents a bit value of a logic bit of the bi-phase modulated signal, where every bit window starts with the transition of the logic state. Logic low is represented by a constant logic state of the bit cycle, while logic high is represented by the transition of the logic state at the center of the bit cycle.
During the wireless charging process, the bi-phase modulated signal is transmitted in a back-scattered manner, from a wireless power receiver to a wireless power transmitter, thus decreasing the amplitude of the bi-phase modulated signal and increasing the waveform distortion of the bi-phase modulated signal. However, the existing bi-phase modulation decoding technology is only applied to general communications with large enough amplitude of the bi-phase modulated signal. So it is not applied to decoding in the wireless charging process, and it has other disadvantages such as occupying too many hardware resources and having high bit error rate.